Senior Honors Projects, 2010-current

Date of Award

Spring 2014

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Integrated Science and Technology

Advisor(s)

Louise Temple

Stephanie Stockwell

Nathan Wright

Abstract

Bordetella avium is a gram-negative bacterial pathogen that colonizes the upper trachea of turkeys and causes bordetellosis. Two large, novel proteins denoted as BAV1944 (447 kDa) and BAV1945 (650 kDa) are suspected to play a role in B. avium virulence. BAV1944 and BAV1945 appear to be secreted through an atypical SecA-dependent type I secretion system and have GD-rich nonapeptide repeats that are signature features of RTX proteins. BAV1945 also has a domain of unknown function that shares structural similarity to the self-processing cysteine protease domains in Clostridium difficile toxin B and the multifunctional autocatalytic repeat-in- toxin (MARTX) toxin in Vibrio cholera. We found that bav1945 and the first gene of the type I secretion system, bav1940, are transcribed at 37°C, implicating their expression under normal host physiological temperatures. However, a derivative of 197N-2 lacking the bav1944 and bav1945 genes (∆bav1944-5) exhibited wild-type levels of growth, serum resistance, tracheal binding affinity, and production of ciliary apoptosis. Our results may suggest that BAV1944 and BAV1945 act as supplementary toxins during infection as opposed to being primary virulence factors.

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